Drop pit apparatus



Oct. 13, 1953 L. H. HoLDi-:MAN ET AL 2,655,115

DROP PIT APPARATUS Filed Aug. 24, 195o 2 sheets-sheet 1 Oct. 13, 1953 l.. H. HOLDEMAN ET AL 2,655,115

DROP PIT APPARATUS 2 Sheets-Sheet 2 Filed Aug. 24, 1950 uf www mw@ M, Wdh y L @ww Patented ct. 13, 1953 DROP PIT APPARATUS Lloyd H. Holdeman and Hugh K. Hybargcr,

Muskegon, Mich., assignors to Manning, Maxwell & Moore, Inc., Muskegon, Mich., a corporation of New Jersey Application August 24, 1950, Serial N0. 181,265

Claims.

The invention relates to drop pit apparatus of the type used in railroad shops for removing, replacing and repairing the trucks or wheels of locomotives and other vehicles and for transferring the truc-ks and wheels between the various service tracks of the shop.

One object of the invention is to provide improved elevator mechanism for drop pit apparatus of the above general character which is simple in construction, eiiicient in operation, inexpensive to maintain, and which is capable of being operated and controlled with a high degree of accuracy.

Another object is to provide a dual elevator mechanism for drop pit apparatus which provides optimum lifting capacities and raising and lowering speeds for the dilerent operating ranges of the apparatus.

It is also an object of the invention to provide drop pit elevator construction which is particularly well adapted to the use of hydraulic lifting mechanisms and to take advantage of the smooth action and easy and accurate control afforded by such mechanisms. ln this connection it may be noted that drop pit apparatus utilizing hydraulic elevator mechanism is disclosed and claimed in the copending applications of Schramm and Holdeman, Serial No. 678,348, now Patent No. 2,520,968, and Holdernan, Serial No. 678,349, now Patent No. 2,520,969, both iiled June 2l, 1946, and in the Holdeman and Hybarger application, Serial No, 181,264, filed August 2li, 1950. The present invention represents further developments and improvements in apparatus of the type disclosed. and claimed in the above applications.

Other objects and advantages of the invention will become apparent from the following detailed description of the preferred embodiment illustrated in the accompanying drawings, in which:

Fig. 1 is a side elevational view of drop pit apparatus embodying the features of the invention, the apparatus being shown with the elevator and drop tables raised to their upper limit positions.

Fig. 2 is an end view of the apparatus showing the elevator and drop tables lowered to transport position.

Fig. 3 is a side view ofthe apparatus with the drop table lowered and the elevator table in its upper limit position.

Fig. 4 is a side elevational view of the apparatus showing both the elevator and drop tables lowered to transport position.

While the invention is susceptible of various modiiications and alternative constructions, we have shown in the drawings and will herein describe in detail the preferred embodiment, but it is to be understood that we do not thereby intend to limit the invention to the specic form disclosed, but intend to cover all modifications and alternative constructions falling within the spirit and scope of the invention as expressed in the appended claims.

For purposes of illustration, the invention has been shown as incorporated in apparatus adapted to operate in a pit il! which intersects and eX- tends beneath a series of service tracks Il such as are commonly provided in railroad repair shops. To permit locomotives or other vehicles to be run over the pit on a service track and their wheels or trucks positioned for lowering within the pit, a drop table l2 is provided for bridging the gaps in the service tracks at the various pit intersections.

The drop table l2 may be or any preferred type such, for example, as shown in the applications above referred to. The pit table illustrated comprises a generally rectangular frame having a floor portion I3 supported on heavy structural members I4 disposed transversely of the pit Iii. For supporting the table in pit bridging position, latch bars l5 are slidably mounted on the table so that they may be projected to rest on ledges It provided in the pit walls. When the table is to be lowered the latch bars are withdrawn to the retracted position in which they are shown in Fig. 2.

Any preferred type of actuating mechanism may be utilized for projecting and retracting the latch bars i5. In the exemplary apparatus the latch bar actuating mechanism is of the hydraulically operated type comprising a double acting piston and cylinder actuator Il operatively connected with the latch bars by a linkage i3. Pressure iiuid is supplied to the actuator il in this instance by a hand pump i9 through a suit` able direction valve (not shown) which determines the direction of movement o1"- the latch bars. The pump i9 is conveniently mounted on the drop table and is provided with an upright operating lever or handle 2G which may be removed after the table is locked in place.

For the accommodation of vehicles to be serviced, the table l2 is provided on its upper face with rails 2| spaced apart to valine with the rails of the service track il. Thus, when the drop table l2 is bridged across the pit the rails 2i eX- tend the service tracks across the pit so that A'the vehicle to be serviced may be run over the pit.

Drop pit apparatus of the type with which the present invention is concerned is usually provided with elevator means for raising and lowering the drop table l2 and also with means for transporting the table along the pit for association with any selected one of the service tracks of the shop. For this purpose the elevator means is mounted on a carriage 25 equipped with hanged wheels 26 adapted to run on rails 2l forming a track at the bottom of the pit Hi. Power actuated means such as motor M may be provided for driving the carriage on the pit track. As herein shown, current for operating the motor is supplied by way of a cable 23 running over a" spring actuated take-up reel 29 mounted on the carriage.

The advantages of equipping drop pit apparatus with dual elevator mechanisms for light duty high speed operation and heavy duty slow speed operation are explained in detail in the applications hereinbefore referred to and various organization including such mechanisms are disclosed and claimed therein. Among those advantages are the substantial structural simplification with attendant reduction in initial costs. Moreover, each elevator mechanism may be constructed to function most efficiently under the load it is required to handle. ln accordance with the present invention, the utility of such dual elevator mechanisms is further extended by associating them with the other elements of the apparatus in a novel and advantageous manner. More particularly, the pit carriage 25 is provided with a vertically movable structure 3S, conveniently called an elevator table, which is arranged to carry both a light duty elevator mechanism 3 i, a heavy duty elevator mechanism 32 and power means for operating both mechanisms.

In the preferred form of the apparatus illustrated, the light duty mechanism 3| is constructed to provide an operating range such that the elevator table may be raised and lowered between the upper limit position in which it is shown in Figs. 1 and 3 and the lower limit or transport position in which it is shown in Figs. 2 and 4. In the latter position the elevator table is adapted to rest on the carriage 25 and the elevator mechanism is relieved of its load.

The heavy duty elevator mechanism 32, on the other hand, is arranged for raising and lowering the drop table |2 relative to the elevator table. To facilitate the disconnection and reconnection of vehicle trucks and wheels, the elevator mechanism 32 is constructed to provide an operating range such that it can lift the drop table |2 substantially above the level of the service track, as shown in Fig. l. lt will be understood, of course, that such lifting of the drop table takes place only when the elevator table 3Q is in its upper limit position. In the lower limit position of the elevator mechanism the drop table is supported directly on the elevator table and the elevator mechanism is relieved of its load.

The elevator table 30 as shown comprises a rigid generally rectangular frame somewhat shorter Iand narrower than the carriage 25. To relieve the elevator mechanism 3| of unnecessary strains, guiding means is provided for confining the movements of the table to a vertical plane. Such guiding means preferably comprises a plurality of upright columns 35 mounted on the carriage 25 and coacting with suitable guideways 3B provided on the table 30. In the particular apparatus illustrated, four of the columns 35 are provided, one adjacent each of the four corners of the carriage 25 for cooperation with the similarly located guideways 3G cn the tabie.

Provision is made for relieving the elevator mechanism 3| of strain when the elevator mechprojected into engagement with ledges 38 provided on the columns 35. When the elevator table is to be lowered to transport position the latches 3l are retracted clear of the ledges, thus transferring the table load back to the elevator mechanism 3 The elevator mechanisms 3| and 32 are preferably of the hydraulically operated type. Thus, as shown, the mechanism 3| comprises a plurality of hydraulic actuators, four in the present instance, each including a cylinder 4|) with a Working piston 4| having its piston rod i12 projecting from the lower end of the cylinder. Each cylinder is provided with a flange 43 for convenient attachment to a cross member forming a part of the table 30 land the piston rod 42 is adapted to bear at its lower end on a cross member 44 provided on the carriage 25. Accordingly, when pressure fluid is admitted to the upper end of the cylinder dil, the cylinder and table 30 are moved upwardly. The table may be lowered by gravity by opening the upper end of the cylinder and allowing fluid to drain therefrom. Alternatively, pressure fluid may be introduced into the lower end of the cylinder to effect -a positive downward movement of the table.

The elevator mechanism 32 likewise comprises a series of hydraulic actuators each comprising a cylinder 45 secured to the table 30 in an upright position as by a flange 46 on the cylinder. Each cylinder has a working piston 4l with its piston rod 4S projecting from the upper end of the cylinder. In the present instance four such cylinders are mounted on the table so as to engage directly with the lower anges of the beams i4 of the drop table |2. When fluid under pressure is admitted to the lower ends of the cylinders 45, the pistons and their rods are shifted upwardly, thus imparting upward movement t0 the drop table l2. Upon exhaust of fluid from the lower ends of the cylinders the drop table is lowered. Such lowering may be effected either by gravity or by introduction of pressure fluid into the up per ends of the cylinders 45.

Pressure iiuid for operating the elevatoi` mechanisms is supplied in the present instance by a pump P driven by an electric motor Ml. The motor and pump are preferably mounted on a base 3B carried on and movable with the elevator table 30. The base 43 may conveniently constitute a reservoir for the iiuid used in the system.

Preferably pressure fluid operated means is also provided for projecting and retracting the latch pars 3l. Such means may conveniently comprise a cylinder 5S having its working piston connected by a piston rod 5| on a crank arm 52 fast on a rockshaft 53 journalled on the table 3B. Other crank arms on the rockshaft are connected by links 5@ with the latch bars 3l so as to move all the hars in or out simultaneously when the shaft is rocked in one direction or the other.

Suitable controls are provided for initiating and interrupting the operation of the various actuators as required. Controls especially well suited for that purpose are disclosed in our copending application Serial No. 181,264, filed August 24, 1950. By reference to that application it will be seen that the controls for the dual elevator mechanisms are interlocked and coordinated with each other and with the control for the latch actuator so that the proper operating sequence is insured at all times.

It will be apparent from the foregoing that the invention provides drop pit apparatus oi novel and advantageous construction particularly well adapted for the use of hydraulically actuated dual elevator mechanisms. By mounting the elevator mechanisms and their power drive means on the elevator table, simplicity of construction is attained and maintenance is greatly simplified. The operations of the elevator and associated mechanisms may be readily coordinated to insure emcient and safe operation at all times. Through the provision for transferring the support of the elevator table directly to the carriage the light duty elevator mechanism is effectively protected from excessive strains when the heavy duty mechanism is used for lifting heavy loads.

We claim as our invention:

i. Apparatus for use in a pit intersecting and extending beneath a service track comprising, in combination, a drop table dimensioned to span the pit bridge the gap in the service track, means for release-bly latching said drop table in pit bridging position, a carriage movable in said pit below said drop table, an elevator table mounted on said carriage for vertical movement, elevator mechanism mounted on said elevator table for raising and lowering the table relative to said carriage, means carried by said elevator table and cooperating` with means on said carriage when the table is in a raised position for supporting the table independently of said elevator mechanism. and other elevator mechanism mounted on said elevator table operative to raise and lower said drop table.

2. Apparatus for use in a pit intersecting and extending beneath a service track comprising, in combination, a drop table dimensioned to span the pit and bridge the gap in the service track, means for releasably latohing said drop table in pit bridging position, a carriage movable in said pit below said drop table, a plurality oi cylinder and piston mechanisms interposed between said elevator table and said carriage for raising and lowering the table relative to the carriage, other cylinder and piston mechanisms mounted on said carriage operative to raise and lower said drop table, and means for supporting said elevator table in a raised position independently of said first mentioned cylinder and piston mechanisms while said other cylinder and piston mechanisms are in ope-ration.

3. In a drop pit apparatus, in combination, a carriage adapted to travel in a pit intersecting a service track, a drop table dmensioned to bridge the gap in the service track, means on said carriage for raising and lowering said drop table between a pit bridging position and a transport position, said raising and lowering means comprising an elevator table adapted to rest on said carriage in its lower limit position, a plurality of upright columns mounted on said carriage and 0 Number coacting with said elevator table to guide the same for vertical movement, hydraulically actuated mechanism mounted on said elevator table operative to raise and lower that table between an upper limit position and said lower limit position, other hydraulically actuated mechanism mounted on said elevator table operative to raise and lower said drop table, and latch means on said elevator table engageable with said columns for supporting that table adjacent said upper limit position.

4. In a drop pit apparatus, in combination, a carriage adapted to travel in a pit intersecting a service track, a drop table dimensioned to bridge the gap in the service track, means on said carriage for raising and lowering said drop table between a pit bridging position and a transport position, said raising and lowering means comprising an elevator table adapted to rest on said carriage in its lower limit position, a plurality of upright columns mounted on said carriage and coacting with said elevator table to guide the same for vertical movement, hydraulically actuated mechanism mounted on said elevator table operative to raise and lower that table between an upper limit position and said lower limit position, other hydraulically actuated mechanism mounted on said elevator table operative to raise and lower said drop table, a plurality of movable latch bars mounted on said elevator table, said latch bars when projected acting to support the elevator table on said columns and being retractible to release the elevator table for movement by said first mentioned hydraulic mechanism, and power operated means for projecting and retracting said latch bars.

5. In a drop pit apparatus, in combination, a carriage adapted to travel in a pit intersecting a servicetrack, a drop table dimensioned to bridge the gap in the service track, means on said carriage for raising and lowering said drop table between a pit bridging position and a transport position, said raising and lowering means comprising an elevator table adapted to rest on said carriage in its lower limit position, a plurality of upright columns mounted on said carriage and coacting with said elevator table to guide the same for vertical movement, hydraulically actuated mechanism mounted on said elevator table operative to raise and lower that table between an upper limit position and said lower limit position, other hydraulically actuated mechanism mounted on said elevator table operative to raise and lower said drop table, a plurality of movable latch bars mounted on said elevator table, said latch bars when projected acting to support the elevator table on said columns and being retractible to release the elevator table for movement by said first mentioned hydraulic mechanism, a hydraulic actuator for projecting and retracting said latch bars, and a common source of pressure fluid carried by said table for supplying said table raising and lowering mechanisms and said latch bar actuator.

LLOYD I-I. HOLDEMAN. HUGH K. HYBARGER.

References Cited in the file of this patent UNITED STATES PATENTS Name Date 1,450,702 ous m1 Apr. 3, i923 

